Super Street Network

Brabus Rocket 800

Seven League Boots

Back in September 1984, Brabus founder, Bodo Buschmann, took me for a wild ride in a dark-blue 190E with the V8 motor from a 500SE shoehorned under its short bonnet. This unholy marriage of the smallest Mercedes model with a tuned version of the biggest Mercedes engine was a recipe for some serious action.

Bodo did a fast U-turn on the street outside his company, steering as much with his right foot as the tiller. We left a cloud of vaporized Pirelli rubber hanging in the air. Then we rocketed up the local autobahn at speeds far in excess of anything the 190’s designers had ever envisioned for their new baby.

For me, this was a spectacular initiation into the world of Brabus. Big-displacement engines in small, relatively light cars is an age-old recipe, but for the smallest car ever to wear the three-pointed star, this was just the beginning.

In the ensuing years, Brabus cars with big engines have been getting more powerful and faster, creating several Guinness World Record entries for fastest Saloon, Estate, SUV and so on along the way.

The Brabus E V12 is now in its third incarnation, and the 730-hp version that was used to set their most recent record has now been eclipsed by a car wearing the Brabus 800 designation.

However, for many Brabus fans, the car that really captured their imagination was the first Brabus Rocket of 2005. Based on the first-generation CLS, the Rocket formula gave the stylish four-door coupe real attitude, turning it into a fire-breathing monster with teeth and claws to match.

Six years down the line, the Rocket 2 made its debut at the 2011 Frankfurt Motor Show, and I drove the precious prototype two weeks before it was wheeled onto the stand.

Standing in the middle of a long defunct steel mill in the heart of Germany’s industrial Ruhr region, the battleship grey Rocket 800 looks like something that has just landed from outer space. Its sleek lines stand out in stark contrast to the broken buildings and rusty ironwork of this rough neighborhood.

Yet, the second-generation CLS looks far more at home here than its rather feminine looking predecessor could ever be. Enhanced by the aggressive visage of the Brabus Rocket 800 conversion, Mercedes designer, Hubert Lee’s taut and muscular CLS now has the stance of a street fighter, and the firepower to back it up.

Under the bonnet, Brabus uses the very latest full-fat version of its bi-turbo V12 powerhouse. That means 800 hp at 5500 rpm with 812 lb-ft of torque electronically limited down from a potentially axle snapping 1,048 lb-ft.

Installing the V12 motor went down more or less the same path as with the E-Class. “The chassis does not require any modifications as such,” explained Jörn Gander, Brabus’ Deputy Development Chief. “We substitute the alloy front subframe for an steel one to take the extra weight and torque, and use the E V12 mountings.”

The bespoke stainless steel sports exhaust has 200-cell free-flow metal catalysts and a valve control bypass that opens when you go to full throttle for more power and sound.

The big mechanical change is the gearbox. No ancient five-speed automatic this time. Instead, Brabus has finally done what many enthusiasts have been waiting for, uprating and adapting the seven-speed automatic gearbox to work with the mighty V12.

Starting with the latest wet-clutch AMG Speedshift MCT from an S63 AMG, with its 664 lb-ft torque capacity, Brabus strengthened the salient components to bear the onslaught of up to 812 lb-ft.

While the internal strengthening work was a fairly routine task, matching a set of disparate engine and gearbox components that were never meant to work together was more easily said than done.

“In the simplest terms, we had to modify the rear of the V12 motor’s block, and an all-new flywheel we machined from a solid billet matches this to the wet-clutch system of the gearbox,” explained Jörn. “We then added a larger-capacity cooling system for the gearbox oil.”

While in empirical terms, even the standard V12 bi-turbo motor has ample torque to cover its five forward ratios, the extra two gears give it “seven league boots” in the most literal sense.

Seven league boots appear in all three of the books of the Bartimaeus Trilogy, worn by the mercenary Verroq. In The Amulet of Samarkand, Bartimaeus remarks that the boots were created in Medieval Europe by imprisoning a djinni in each boot, who could operate on a theoretical eighth plane. Because of this, the normal rules of time and space do not apply to them.

When it comes to sheer performance, that mythical description practically applies to the Rocket 800. With its traction aided by a 40 percent limited-slip differential, the 4,365-pound Rocket 800 blasts through the 62-mph and 124-mph markers in 3.7 and 9.8 seconds respectively, and reaches 186 in 23.8 seconds on its way to a top speed of 230 mph.

While these numbers are a tad faster than the E V12’s thanks to the better gearing and lower frontal area, they do not show the subjective improvement in performance from behind the wheel.

The intermediate gears are stacked closer together, which makes the big V12’s power delivery feel sharper and more immediate. As the engine stays in its sweet spot more of the time, it accelerates more aggressively in the mid-range. Between 62 and 124 mph for instance, the perceived thrust is simply mind-boggling and is sustained in a way that no high-revving, naturally aspirated supercar can match.

Best of all, its voice is subtly altered. The baritone V12 now snaps from gear to gear much faster than the five-speeder slurs its ratios, so its throaty roar gets back on song with greater verve.

“Previously, we offered a shorter final drive ratio that either gave you better acceleration, but limited top speed to 196 mph, or the taller ‘Nardo’ ratio that went to 230 mph. The standard ratio was in between at 212 mph,” explained Jörn.

“The standard 2.65:1 rear differential ratio works perfectly with the seven-speed gearbox,” he said. “Ratios one to six have the same speed range as the original five, and seven is the equivalent to the Nardo ratio. In the meantime, the closer intermediate ratios deliver better acceleration, while fuel economy at cruise benefits from the taller Seventh gear.”

“As always, the biggest issue was getting all the electronics to work perfectly,” said Jörn. While the mechanical changes are very much a Mercedes and Brabus parts bin affair, there is no “cheat sheet” for the electronic nightmares all this throws up in a modern car laden with a plethora of electronic control units that need to speak the same language, and be on the same page at any given time.

Modern cars transfer their data via a high-speed CAN-BUS network and in a car as sophisticated as a Mercedes, there can be up to two dozen separate ECUs sending data streams back and forth on the network.

“We practically have to recalibrate every ECU in the car to make sure they are shaking hands correctly,” Jörn explained. “It is not just that the checksums have to add up, but we have to ensure there are no data collisions within the network that will throw up a fault code and possibly put the system into ‘limp home’ mode.”

“For a start, the CLS was never meant to have a V12 motor, then the V12 was never meant to work with the seven-speed auto, and so on,” he continued. “The ECUs in cars with four-, six-, eight- and 12-cyinders will all be coded differently as the data streams and operating parameters are different.”

“And that is just the start of the problems. In a modern Mercedes, there are also ECUs that control things like the air-conditioning. All rely on an ID Code, physical numbers and a message that have to be delivered with special timing to communicate correctly. When all these work correctly, the corresponding ECUs on the network will understand the message correctly,” he said.

“The prioritizing of data is another issue here, and the system is set up to know that in an overheating situation, keeping the air-con at [72 degrees] is not as important as engine temperature.”

“In the end, it is the less obvious things that you have to think of,” said Jörn. “For instance, you have to remember that the V12 motor has a lower redline than the normally aspirated 6.2-liter V8, so the MCT gearbox ECU has to be recalibrated accordingly to upshift at lower engine speeds.”

Where the CLS63 AMG uses gas dampers and coil springs in front with air suspension at the rear, the Rocket 800 uses the same bespoke Bilstein coilover system as the E V12. This features height adjustment via its spring pans, and gas dampers with 10-position bounce and rebound adjustment. “This setup gives us the flexibility to tailor the ride and handling for individual owners,” said Jörn.

The brakes use massive 380mm cross-drilled discs in front with 360mm discs at the rear clamped by 12- and 6-pot monoblock alloy calipers respectively. While 20-inch wheels are fashionable and look good, 19s are the optimum size to tackle speeds beyond 200 mph.

Thus, like the E V12, the Rocket 800 sits on 9.5x19 Brabus MONO block F wheels all round and shod with 255/35 and 285/30 Yokohama Advan Sport rubber. This is for space reasons as well as the TÜV homologation for the Rocket 800’s very high top speed.

All the aero parts are made from carbon fiber, and start with a completely new nose section with the huge air intakes needed to feed the monster engine’s larger primary radiator and the engine and gearbox oil coolers. The area above the grille has four small intakes that feed extra ram air to cool the engine bay. The front arches and track are the same width as the CLS63 AMG.

The new side sills lead to the wider rear arch flares, which make the car 40 mm wider overall, and the new rear valance with integrated carbon-fiber underbody diffuser. The rear wing is also made from carbon fiber and sits on two machined alloy stays bolted to the reinforced bootlid.

While such a wing is a bit “Fast and Furious” for Brabus, wind tunnel testing underlined the fact that it had to be that high off the bootlid to make the CLS stable at speeds over 186 mph.

The Rocket 800’s luxurious cabin is wrapped and trimmed to perfection in fine Brabus leather with piano wood trim inserts. It is a supremely comfortable place from which to conduct the serious business of compressing time and distance.

Bigger, better, faster, more! The Brabus bi-turbo V12 story just keeps on growing, and with the Rocket 800, it has reached a pinnacle in image as well as outright performance.

To my surprise, a friend who has three Brabus cars, including a CL and an original Rocket with 730-hp V12S motors, e-mailed me to ask about the Rocket 800 the day after I drove it. I wondered how he even knew it existed as five days later, there is still nothing on the Internet. But that, it seems, is the draw of the legendary Brabus Rocket.